# Example Physics Problems and Solutions

Learning how to solve physics problems is a big part of learning physics. Here’s a collection of example physics problems and solutions to help you tackle problems sets and understand concepts and how to work with formulas:

Physics Homework Tips
Physics homework can be challenging! Get tips to help make the task a little easier.

### Newton’s Equations of Motion Example Problems

• Equations of Motion – Constant Acceleration Example
This equations of motion example problem consists of a sliding block under constant acceleration. It uses the equations of motion to calculate the position and velocity of a given time and the time and position of a given velocity.
• Equations of Motion Example Problem – Constant Acceleration
This example problem uses the equations of motion for constant acceleration to find position, velocity and acceleration of a breaking vehicle.
• Equations of Motion Example Problem – Interception
This example problem uses the equations of motion for constant acceleration to calculate the time needed for one vehicle to intercept another vehicle moving at constant velocity.
• Vertical Motion Example Problem – Coin Toss
Here’s an example applying the equations of motion under constant acceleration to determine the maximum height, velocity and time of flight for a coin flipped into a well. This problem could be modified to solve any object tossed vertically or dropped off a tall building or any height. This type of problem is a common equations of motion homework problem.
• Projectile Motion Example Problem
This example problem shows how to find different variables associated with parabolic projectile motion.
• Accelerometer and Inertia Example Problem
Accelerometers are devices to measure or detect acceleration by measuring the changes that occur as a system experiences an acceleration. This example problem uses one of the simplest forms of accelerometer, a weight hanging from a stiff rod or wire. As the system accelerates, the hanging weight is deflected from its rest position. This example derives the relationship between that angle, the acceleration and the acceleration due to gravity. It then calculates the acceleration due to gravity of an unknown planet.

### Friction Example Problems

These example physics problems explain how to calculate the different coefficients of friction.

Weight In An Elevator
Have you ever wondered why you feel slightly heavier in an elevator when it begins to move up? Or why you feel lighter when the elevator begins to move down? This example problem explains how to find your weight in an accelerating elevator and how to find the acceleration of an elevator using your weight on a scale.

Equilibrium Example Problem
This example problem shows how to determine the different forces in a system at equilibrium. The system is a block suspended from a rope attached to two other ropes.

Equilibrium Example Problem – Balance
This example problem highlights the basics of finding the forces acting on a system in mechanical equilibrium.

Force of Gravity Example
This physics problem and solution shows how to apply Newton’s equation to calculate the gravitational force between the Earth and the Moon.

### Coupled Systems Example Problems

Simple Atwood Machine

Coupled systems are two or more separate systems connected together. The best way to solve these types of problems is to treat each system separately and then find common variables between them.
Atwood Machine
The Atwood Machine is a coupled system of two weights sharing a connecting string over a pulley. This example problem shows how to find the acceleration of an Atwood system and the tension in the connecting string.
Coupled Blocks – Inertia Example
This example problem is similar to the Atwood machine except one block is resting on a frictionless surface perpendicular to the other block. This block is hanging over the edge and pulling down on the coupled string. The problem shows how to calculate the acceleration of the blocks and the tension in the connecting string.

### Charge and Coulomb Force Example Problems

Two charges separated by one centimeter experiencing a force of repulsion of 90 N.

Electrical charges generate a coulomb force between themselves proportional to the magnitude of the charges and inversely proportional to the distance between them.
Coulomb’s Law Example
This example problem shows how to use Coulomb’s Law equation to find the charges necessary to produce a known repulsive force over a set distance.
Coulomb Force Example
This Coulomb force example shows how to find the number of electrons transferred between two bodies to generate a set amount of force over a short distance.

### Light and Energy Example Problems

Energy and Wavelength Example
This example shows how to determine the energy of a photon of a known wavelength.